#include<stdio.h>
double jc_double(int n);
long jc_long(int n);
int main()
{
    int n;
    double sum=0;
    scanf("%d",&n);
    for(int i=0;i<=n;i++)
        sum+=1.0/jc_double(i);
    printf("%.8lf",sum);
//	printf("jc_double(20) = %lf",jc_double(20));
//	printf("\n");
//	printf("jc_long(20) = %ld",jc_long(20));
    return 0;
}

double jc_double(int n)
{
    double sum=1;
    for(int i=1;i<=n;i++)
        sum*=i;
    return sum;
}

long jc_long(int n)
{
    long sum=1;
    for(int i=1;i<=n;i++)
        sum*=i;
    return sum;
}

